1. Field of the Invention
This invention relates to a heat-insulating engine with swirl chamber having main combustion chambers and swirl chambers in an internal combustion engine.
2. Description of the Prior Art
As a prior art heat-insulating structure of a swirl chamber in an internal combustion engine, there is a system disclosed in the gazette of Jap. U.M. Laid-Open No. 59--21024 of which the present invention is concern. The swirl chamber has an eddy flow chamber in a cylinder head, an entire combustion chamber of the eddy flow combustion chamber is made of ceramic material and at the same time an air layer is formed at a substantial part of a fitted portion between the combustion chamber and the cylinder head made of ceramic material. An end facing a cylinder side at a fitted part between the combustion chamber and the cylinder head is gas-sealed with a seal member and an insertion part between the combustion chamber and its inserted unit is gas-sealed with the seal member.
A swirl chamber structure of an internal combustion engine, in particular, a swirl chamber structure defined by a swirl chamber ceramic material and having an improved thermal efficiency of the engine, improved heat-resistance characteristics and an improved durability of the swirl chamber is disclosed in the gazette of Jap. Pat. Laid-Open No. 61--123,714, for example. The swirl chamber structure of an internal combustion engine which is disclosed in the above-mentioned gazette is comprised of an upper ceramic body and a lower ceramic body fitted to said upper ceramic body, wherein a metallic annular ring is fitted to the outer circumferences of the upper ceramic body and the lower ceramic body, and the inner circumferential surface of the annular ring corresponding to the fitted surfaces of the upper ceramic body and the lower ceramic body is provided with an annular concave part.
In addition, the swirl chamber of an internal combustion engine of which an inner circumferential surface is formed by ceramic material is disclosed in the gazette of Jap. Pat. Laid-Open No. 60--212,614, for example. The swirl chamber of the internal combustion engine disclosed in the above-mentioned gazette is constructed such that a fitting member having communication holes between the chamber part of a substantial semi-spherical hollow body and the main chamber is made of ceramic material, respectively. The ceramic material at the chamber part composed of heat-insulating ceramics is casted with metal and at the same time the casted metal is simultaneously formed with a cylindrical projecting portion, and the ceramic fitting member composed of heat-resistant ceramics is shrinkage fitted to an inner side of the projection. In addition, a heat-insulating layer is partially arranged between the inside part of the cylindrical projection and the ceramics of the fitted part.
In general, in the case of combustion in a heat-insulating engine, the thermal energy from the combustion chamber may not be dispersed due to the heat-insulating structure of the engine, resulting in that the wall surface of the combustion chamber provides high temperature, a deteriorated efficiency and a deteriorated combustion speed. As regards the deteriorated gas intake efficiency, its cause consists in the fact that the intake air accepts heat from the wall surface of the combustion chamber and the air is hard to enter the combustion chamber. There is a problem as to how to construct the combustion chamber in such a way as the intake air may not accept heat from the wall surface of the combustion chamber or the wall surface of the intake port in order to prevent a reduction of a gas intake efficiency. The deterioration of the combustion speed is caused by an excessive increase in of temperature of intake air and a shortened ignition delay time of fuel. So, in order to prevent any deterioration of the combustion speed, there is a problem as to how to restrict the increase temperature of intake air and set the ignition delay time of fuel to a preferable period. In addition, there is a principle that a high temperature combustion of fuel may reduce an amount of discharged substance such as smoke; and NOx etc. by restricting the excess air ratio to 2 to 1.5, performing a high temperature combustion of mixture gas without making any fast leaning of mixture and decreasing its temperature rapidly as the piston descends.